CANADIAN TRANSLATION OF FISHERIES AND AQUATIC SCIENCES

No. 4621

Studies on the population biology of the flatfish, Limanda herzensteini JORDAN et SYNDER,

in Niigata region. II. Maturity and spawning

by K. Wada

Original Title: Niigata-ken okiaisan magarei no shigenseibutsugakuteki kenkyu. II. Seijuku to sanran

From: Nihonkaiku Suisankenkyusho Kenkyuhokoku (22): 45-57, 1970

Translated by the Translation Bureau (KFM/PS) Multilingual Services Division

Department of the Secretary of State of Canada

Department of Fisheries and Oceans Newfoundland Region St. John's, Nfld.

1980

22 pages typescript

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WADA Katsuhiko TITLE IN ENGLISH - TITRE ANGLAIS

Studies on the population biology of the flatfish, Limanda herzensteini JORDAN et SNYDER, in Niigata region. II. Maturity and spawning

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Niigata-ken okiaisan magarei no shigenseibutsugakuteki kenkyu. II. Seijuku to sanran

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Bulletin of the Japan Sea Regional Fisheries Research Laboratory

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Nihonkaiku Suisan Kenkyusho Kenkyuhokoku (Bulletin of the Japan SeaRegional Fisheries Research Laboxa tory), No. 22, pp. 45-57, March 1970.

STUDIES ON THE POPULATION BIOLOGY OF THE FLATFISH,.

Limanda herzensteini JORDAN et SNYDER, IN NIIGATA REGION

II MATURITY AND SPAWNING

Katsuhiko WADA1

Abstract

The gonads of the flatfish, Limanda lterzensletiji J9RM.\, et,SNYDEs, were observe r to obtain basic

information on the breetling biology of this speciés.Th e iilaterials, 598 in total were collected from,otifNiigata Prefecture during January 196S to tlpril'i9G9: The gonads of all the specimens Ni•erè weighà^ilin fresh state in the laboratory. Histological observations were made on some samples,àtid.the ov.a

diam(--ter was,measured. The following results were obtained. ;., ,, ..

(1) The spawning season extends from late February to early May. The peak of..spà>yning wns

in \larch and April>(3) Therè were two modes in the oea diameter frequency distribution at the spteti}'ning season.

The mode of the smaller diameter consists of the yolk granulé: stage ova and that of the larger one

contains the matured and ripened eggs.

(3) The estimated number of the ova in the rnôst niâtured batch increa'sed with the increasè of

the standard body length, the body weight and the ovary weight respectively.

(4) From the examination of 139 females at the spawning season, it seemed that hall of them

were matured at 140 mm in standard body length.

1. Introduction

Ehe, Ehe-It is said that in Sendai Bay,right-eyed flounder Limanda herzen-

steini JORDAN et SNYDER spawnsbetween March and May in shallow waters about

1Present address: National Pearl Research Laboratory, Kashikojima, Ago-

cho, Shima-gun, Mie Prefecture, Japan.

SEC 5-25 (Rev. 6/78)

2

ten miles off the coast (KAWASAKI and HATANAKA, 1951). On the other hand,

in the Sea of Japan, according to OUCHI and OGATA (1960), spawning of (p.46)

this fish species peaks in May. However, it appears that there has been

no report describing in detail the spawning season of the species. Nor

has any study been so far carried out on its maturation process or spawning

mode. The preceding report of this series (W.ADA, 1970) dealt with age and

growth of L. herzensteini. The present paper describes the results of a

few observations on the gonads from a limited number of specimens of this

species.

I am grateful to Mr. T. OGATA, Head of the Third Resources Section,

Japan Sea Regional Fisheries Research Lab., for continuous guidance and to

Prof. K. YAMAMOTO, Hokkaido University, for advice in the preparation and

examination of ovary tissue slices. Thanks are also due to Mr. Y. ITO,

Chief of the Resources Division, Japan Sea Regional Fisheries Research Lab.,

who reviewed the manuscript of this report, and to Ms. Y. ROMMA, Technical

Officer, Japan Sea Regional Fisheries Research Lab., who measured the

specimens of this report.

II. Materials and Methods

Our specimens were a total of 598 fish caught by dragnet or

gill net off the coast of Niigata Prefecture between January 1968 and April

1969. These specimens were measured for body weight and standard body

length, then their gonads were saUle-red. and weighed. Values of the ratio

of gonad weight to (body length)3 x 104 were calculated for each specimen

and the values called herein gonad index (G.I.) served as a marker of the

gonad size.

Forty-eight specimens, which were sampled immediately before and

after the spawning season, were examined for ovum diameter as follows: a

cluster of ova were taken from the central part of each specimen's ovary

that had been fixed in 107 formalin and loosened in tap water. Individual

ova having a major axis of more than 0.1 mm were collected at random to

count 100, the ova were placed under a projector and their major and minor

axes were measured to the nearest 0.01 mm, and values of both axes were

averaged to produce ovum diameter.

The gonads used for histological observations were 5atkereci from

a few fish immediately after landing, fixed in 10% formalin, Bouin, or

Gilson's solution, and embedded in paraffin or celloidin. The tissue

blocks were sectioned at 5 to 7 and the sections were stained for

observation with Meyer's hemalum--eosin or Heidenhain's iron hematoxylin--

light green.

III. Results

1. Female

Seasonal changes in G.I. Fig. 1 illustrates monthly distribution

of various G.I. classes, each class being separated by intervals of 2.5,

in female specimens sampled in 1968. Whether an individual had discharged

eggs was determined macroscopically according to the outside appearance of

the ovaries as follows: when the coelowl containing the ovaries inside

was distended LO tke rear part alld ye.t the ovary wall was

slackening because of a lack of generative elements, egg discharge was

considered definite.

As clearly seen from Fig. 1, the ovary of the right-eyed flounder

gradually enlarged from October to January, attained the largest size

between February and April, and sharply reduced in size in May. The data

40

80

50

100

1

ft

80

40

20

20

40

May (n=58)

J un. (h=-27)

Sep. (n=1 7)

.0c t. (n=42)

Dec. (n=-51)

Fig. 1 Monthly distribution of various G.I. classes (female specimens for 1968)

filled column: individuals with transparent eggs

shaded column: individuals con-sidered to have discharged eggs

unfilled column: other individ-uals

4

10 20 30 4 .0 60 70 , G.J.

for February in this figure were based on specimens collected on February

9 and 27. The former specimens had an average G.I. of 9.03, whereas the arty

latter 20.49. None of the former showed. v egg discharge or posses-

sion of transparent eggs. From these findings, in 1968, spawning appears

to have taken place between late February and May. During this period the

frequency of individuals that were considered to discharge eggs was found to 1)e.

as follows: 8.77e in February, 28.67e in March, 46.9% in April, and 10.3%

in May, indicating that March and April were the peak spawning season.

Although data in the two summer months, July and August, were scanty since (p.47)

this period is closed for fishing, the G.I. distribution in the summer is

likely to have followed nearly the sanie pattern as that observed for July

. 9 • : ' ».3( 1 2 1 , . 14 -

2 (2, 1 ; 36 : . -

5

(should read June--Translator's note) or September. In 1969, specimens

were collected twice, once each in February and April. The distribution

patterns in these two months did not markedly differ from those in the cor-

responding times of the preceding year.

Histological observations of ovaries Morphology and the maturation

process of ova for this species were nearly the same as those reported by

YAMAMOTO (1954) for Liopsetta obscura. Hence the results of histological

observations of the ovaries obtained for the right-eyed flounder will be

described according to the system of maturation stages classified by him.

Table 1 Monthly number of female individuals with ovaries of various maturation stages examined histologically

C . -

±fl 'f';:là.;.2.J..Rik 4 etaf,pii)i V.

. _ 1 1

2

-1

5

6

9

10 1 2

11 4

12 1 3

X Month Y Maturation stage

A Peripheral nucleus stage to yolk vesicle stage B Primary yolk globule stage C Secondary yolk globule stage D Tertiary yolk globule stage E Germinal cell-moving stage

F liot quite mature egg stage G Mature egg stage H Ripe egg stage I Total

Based on specimens collected in 1968. Figures in parentheses denote the number observed in 1969.

il

6 ' 2 2

4

4.

1 2 9 9 1

6

Table 1 shows the monthly sLabe5 of occurrence_ oç maiuration

cate.jories divi tied according to the sLa5c.'. of iliyhe,sb Jelva_nucmen

found histologically in the tissue slices. Since the number of the

specimens was rather small, it would be premature to estimate a pattern of

seasonal changes from these results. Nonetheless, when an attempt was made

to relate the histological changes to changes, in the ovary weight which are

represented by the aforementioned seasonal G.I. changes, one can see that

the gradual increase in the ovary weight from the fall to the winter is

histologically expressed in the development pattern of oocytes. It should close, ho Eie. h.a wrii.vu3 e.riri, Lhe-

be noted here thaCindividuals with ovaries ab the secondary yolk globule

avld ab the mature egg stageswere many, whereas those from thetertiary

yolk globule stage to the weinature. egg stage, especially the germinal

cell-moving stage and the yie s'mature egg stage, were very fee. .

Composition of ovum diameter in ovary Ovum diameter composition

was examined with egg clusters sampled from four parts of the ovary as

illustrated .in Fig. 2 to ascertain whether it varies with site of the (p.48) E.be_

ovary. The composition pattern was founenearly the same at these four

sites. As has been aforementioned, since the data for the analysis of

ovum diameter composition were obtained only from specimens collected

near the spawning season, i.e. between January and April, the pattern of

changes in the composition during a whole year could not be obtained.

However, ova of the various maturation stages were observed in these

specimens, enabling Us to estimate changes in the ovum diaméter associated

with maturation from changes in ovum diameter frequency distribution

(Fig. 3). This figure shows the range of approximate size of ova at each

maturation stage as examined histologically. The size, i.e. diameter, of

7

40°lo

20

0

mX

o

e

m

0.4

o

o

X

Q) oo m

^ x e0 0

O ^ X 0x t1 m x x

0.6 0.8 1.0Egg diameter mm

Fig. 2 (top) Frequency distribu-tion of ovum diameter at different

parts of the ovary

Fig. 3 (right) Typical examplesof ovum diameter distribution and

range of ovum diameter in oocytesof various maturation stagesexamined histologically

PN: peripheral nucleus stage

YV: yolk vesicle stage

YG1.2: primary and secondary

yolk globule stages

YG3: tertiary yolk globulestage

MN: germinal cell-moving stage

P"' notquzte,mature egg stageMT: mature egg stageRP: ripe: egg stage

` -------- YGI,2YG3

M NP M E--^M T ^ --^

.1,0.1 0.5 0:9

Egg diameter_, mm

these ova was estimated by comparisons between modes clearly appearing in (p.49)

ovum diameter frequency distribution curves (which were obtained from about

6,. Eh25 specimens that were examinedYfor histological features and for egg

8

diameter) and maturity of oocytes observed in the largest number in the

tissue slices. In right-eyed flounder it is known that development of

yolk globules originating from yolk vesicles is so fast that the yolk

vesicles are hardly detectable; in fact, none of the oocytes could be

asczrbained as being at the yolk vesicle stage. Therefore the given ovum

diameber at the yolk vesicle stage was estimated from those before and after

this stage.

In the ovary of the right-eyed flounder, oocytes in which ova were

less than 0.1 mm in diameter were seen in large numbers throughout the

year. Until these ova developed to reach a diameter of about 0.5 mm, as

hhe. shown in Fig. 3,s/ovum diameter frequency distribution was monomodal. As

the spawning season approached, two modes began to appear, the boundary

lying at a diameter between 0.55 and 0.65 mm. Although ova of this size

correspond to the germinal cell-moving stage to the bokinature egg stage,

in the present study none of the specimens had a mode in this range. Of (p.50)

the two modes described above, the one a small diameter represented in

nearly all cases ova aL the secondary and tertiary yolk globule stages and

in some cases those of the germinal cell-moving stage, whereas the other ret,Tesenke.cl,

we a large diame[er transparent eggs which correspond to the matured and

the ripe egg stages (Plate II--9). Seventeen specimens were observed

to show a definite mode in the range of transparent eggs. Of these, only

one had a single mode, i.e. it carried nothing but ova of less than 0.1 mm

and transparent eggs, whereas all of the others had the other mode near

0.40 to 0.50 mm (Fig. 4). This figure shows the relation between the

position of modes in ovum diameter frequency distribution curves and the

G.I. In the figure, those individuals bimodal in their ovum diameter

' N.48 • -OD

••■

• • ••-

• eiL •---- -•

• -IF• •• $ - • •oo

• •

•

G.I.

50

_ - 0 0.5

, Egg diameter

Fig. 4 Relation between the position of modes in ovum diameter frequency distribu-tion and the G.I.

1.0 M M

100

100

F50

N=139

tdAerde Adide/A Arz A' Ar.._ •

• • 150 200 rnm Standard Length

distribution are marked by two dots joined

together with a straight line, each dot

being at the respective mode position.

Of the two dots,11e.sma11er one denotes

the position of a mode of lower frequency.

The relation between the mode position and Lobe,

the G.I. was founenearly linear in the

range of low G.I. values, but began to fall

into disorder as the G.I. value increased

from about 20. Beyond about this point

bimodal individuals appeared in increasing

numbers. When these findings were con-

sidered together with the relationship

9

between the maturation stage and the diameter of eggs as shown in Fig. 3,

it is estimated that nearly all those individuals having G.I. values

of more than 20 carried oocytes that had developed beyond the secondary

to tertiary yolk globule stage.

Biologically smallest form

of 139 specimens, including mature and immature fish, that were collected

Ute. Fig. 5 shows'body length distribution

30 Fig. 5 Number (N) of mature (shaded column) and immature (unfilled column) female fish of various standard body length

10 classes and ratio (F, unfilled circle) of the mature fish

1 0

zE five different times between February 27 and April 23. Of these

specimens, those which met at least one of the following conditions were as

regarded as mature fish, a‘nel. all of the others immature:.

carry ie9 transparent eggs, (2) beinj deemed to have defligte.13i. discharged

eggs, and (3) a G.I. of more than 20. The third crUekion was based

on the finding of YAMAMOTO (1956) that in Liopsetta obscura, ova in the

ovary of immature fish,though undergoing seasonal changes,never de'yeloped

beyond the primary yolk globularstage and also on the aforementiorieefind-

ing that nearly all right-eyed flounderswith G.I. values of more

than 20 carried ova beyond the secondary yolk globule stage. The standard

body length at which the ratio of mature fish exceeded 50% was about 140

mm and at a length of about 190 mm, 100% of the specimens were mature fish.

The ratios of mature fish in these specimens 12y various ages were as fol- (p.51)

lows: 16% at full 3 years of age, 65% at full 4 years of age, 70% for full

5 years of age, 83% for full 6 years of age, and 100% for full 7 years of

age. In the present study the smallest mature individual had a body

length of 123 mm and was fully four years old. IL carried ripe eggs

and discharged eggs when squeezed at the abdomen.

Number of transparent eggs The number of transparent eggs that

were contained in the ovaries of one individual was determined by gravimetry

as follows: 15 individuals carrying transparent eggs were chosen, one-

gram quantity of a cluster of eggs was weighed out from the same site of

one ovary of each individual as used in the measurements of ovum diameter,

and the number of transparent eggs (A) in the cluster was counted. This

was then multiplied by the weight of the ovaries (1.3) to yield AB, which

is the total number of transparent eggs in one individual. The relation

N=1 5

0 • • 0 GI* •

0 • • 0

• et. 00

• C,

• 0 0 (!,

11

between transparent egg number and body length, body weight, or ovary

weight is demonstrated in Fig. 6. As far as this study is cionderned,

some relationship was observed between the

number of transparent eggs and any one of

the three parameters. The total number of t 104

transparent eggs carried by one individual .0 • E 1

fish ranged from about 3,000 to 100,000.

Male '934- 15n

u MO mrri SI 0 g BW

500-b-`71. '—

frequency distribution of individuals Fig. 6 Relationship be- 'tween number of trans-

having various G.I. classes (at intervals parent eggs carried by one individual and its

of 0.2) in 1968 is shown in Fig. 7. standard body length (SL), body weight (BW), or

Whether an individual had discharged sperm ovary weight (GW)

was macroscopically determined according

to the exterior appearance of the abdomen. Since data in the seasons

other than the spawning period were scanty and since there were. no specimens

in July and August, it would be premature to estimate any pattern of

seasonal changes from this figure. Nonetheless, a certain trend is dis-

cernible: spermary weight suddenly increased from November to December (p.52)

and then gradually decreased from January toward May and June. Individuals

that are considered to have discharged sperm appeared between March and

May, April being the peak which represented 40 7e of the total specimens.

Hence sperm discharge is considered to have taken place between March and

May, the peak being in April, and this coincided with the period of egg e.

discharge in the females. It appears in'male right-eyed flounder that the

gonad weight reached a maximum two to three months before sperm discharge.

Seasonal changes in G.I. Monthly

12

100t

40

m n n J o n.(n_ 5)T

LFh_ -Fe b.(n-28)

Mar : (h;_32)

Apr:,(n_33)

May, (n=34)

p.

^tïï(n^12)

n=3)

0(n=̂ 10)

40L _ -n Nov: (p= 5)

30 nÇlëc;.(.n;^ 7) ^T^ I I ^, n

1.0 2.0 3.0 4.0 5.0 60 7.0G.J.

Fig. 7 Monthly distribution of

various G.I. classes (male in

1968). Shaded column: individ-

uals considered to have dis-

charged sperm. Unfilled column:

other individuals.

HistoloRical observations Histological changes in the spermary

were nearly the same as those reported by YAMAMOTO (1953)

for Liopsetta obscura: at about the time when discharge of spermatozoa

was completed, new spermatogonia appeared on the wall of each spermato-

gonial cyst'and matured nearly equally into spermatocytes, spermatids, and

spermatozoa, though some variation was seen among individual cysts. Hence

in this report the development system of YAMAMOTO (1953) will be used to

discuss seasonal changes. Table 2 shows the monthly frequency of male

individuals having gonads of various maturation stages. In these indi-

viduals the maturation stage of the gonads were classified according to the

type of most developed cells found histologically in the tissue sections.

13

Table 2 Monthly number of male individuals with gonads of various maturation stages examined histologically

5r, 1 ' 2 1 9 »; ' - lu l ii i 1 té.) 11, I tlY'141 eillill

II •. 11 .1-

" 1 10 : 9 . - I el 7(}

• . 3 4 I . 4

f ,, 5 -1 . la) . 6,1)

5 4 1 5

. . 6. 9

9 . 3 . . 3 .

. . 10 2

' 11 1 • 1 - . • 1 1 9 12 2 '

X Month Y Maturation stage

A Primary spermatogonium stage B Secondary spermatogonium stage C Primary spermatocyte stage D Secondary spermatocyte stage E Spermatid stage F Spermatozoon stage G Total

Based on specimens collected in 1968. Figures in parentheses denote the number observed in 1969.

Although the specimen size was very small, the gonads appear to have been

regularly developing. Matured spermatozoa were seen in large numbers of

individuals between February and May, especially in February and March.

The number of individuals that were histologically considered to be in the

stage immediately after sperm discharge was four each in April and May.

IV. Discussion

According to OUCHI and OGATA (1960), May is the main spawning

season of right-eyed flounder in the northern Sea of Japan. It has been

shown in the present study that spawning of this species off Niigata

Prefecture appears to have taken place between February and May in 1968,

• • • • - 1 -"'• • Ej- iil•

14

‘.„

the peak having occurred in March and April. KAWASAKI and HATANAKA (1951)

have reported that the spawning season of right-eyed flounder in Sendai

Bay is between March and May. Therefore the spawning season off Niigata

Prefecture appears to coincide with that in Sendai Bay.

Numerous fish species have been reported to show a bi- or poly-

modal pattern in their ovum diameter distribution and the mode of matura-

tion and spawning for each of these species has been discussed also in Ehe.

numerous reports. Of,these fishes,.'heterosomatous are Hippoglossoides

dubius (ISHIDA, 1957), Pseudorhombus cinnamoneus (MATSUURA, 1962), and

Kareius bicoloratus (MATSUURA, 1969a). WHEELER (1924), who carried out

histological examinations of the ovaries of Pleuronectes limanda, observed

that eggs with yolk coexisted with empty follicles and stated that mature

eggs were not spawned all at one time. In the case of right-eyed flounder,

as the spawning season approached, ovum diameter distribution began to

show a typical bimodal pattern when ova with diameter of less than 0.1 mm,

which have no bearing on spawning, are excluded. In many cases the boundary

between the two modes lay between 0.55 and 0.65 mm, the range of which

corresponded to the germinal cell-moving stage to the not ymature egg stage.

a developmental period frcie, It has been pointed out by YAMAMOTO (1954, 1956), ISHIDA et al. (1959),

and YAMAMOTO and YOSHIOKA (1964) that in many fish species development of

the ova between the germinal cell-moving stage and the ripe egg stage

is generally completed within a short time. This has also been confirmed

in the present histological observations from the finding that the fre-

quency of ova of this developmental period was low.

Judging from the observed patterns of ovum diameter distribution,

two possibilities are conceivable for spawning frequency during a given

(p.53)

15

spawning season of Limanda herzensteini: 1) The flounder spawns twice in

the season, i.e. the two modes shown in the aforementioned ovum diameter

distribution curves correspond to groups of eggs to be discharged on each

of the two spawning occasions. 2) After one group of eggs having a mode

at the large diameter and being in the ripe state have been discharged,

eggs from the other group with a mode at the small diameter mature in

succession to be discharged in a few number of times. If the first pos-

sibility had been happening in the present study, one should have seen a

be ttle_ fairly large number of individuals being in state just before'second

spawning aAlci carryisl a group of ova consisting solely of ripe eggs.

However, of the 17 specimens having a mode in the range of transparent

eggs, only one was such an individual. In other words, the mode at the

small diameter in the bimodal distribution was unlikely to disappear with

ease, suggesting that spawning occurred in the manner of the second pos-

sibility. MATSUURA (1969a) stated that in Kareius bicoloratus,'ovum dia-

meter distribution shows a monomodal pattern for ova of HIcstagesfrom the

yolk globule. stages to the germinal cell-moving stage, but a bimodal

pattern once ripened eggs are formed. He further observed histolog-

ical differences between old and newly formed empty

follicles and examined ovum diaméter compositionsin the ovaries having such

old and new empty follicles. On the basis of these findings, he has

postulated that Kareius bicoloratus spawns according to the aforementioned

second possibility. This postulation was later confirmed by observation

of spawning in a tank (MATSUURA, 1969b). Although in the present study with

right-eyed flounder the number of specimens that were subjected to histo-

logical examination was too small to justify discussion of spawning

16

frequency, the presence of empty follicles could not be detected in any

individuals having a bimodal/Pattern of ovum diameter distribution. Hence

judging from the ovum diameter distribution patterns alone, it is conceiv- in

able that in Limanda herzensteini, likjKareius bicoloratus, spawning takes

place in the manner described above as the second possibility. However,

the present histological observations provided no evidence for this

likelihood and Elie., luesbioyl is sLi.11 un solve-d-

According to a study on the frequency distribution of right-eyed

flounder individuals carrying mature eggs in the Tohoku region of the

Pacific Ocean, the biologically smallest form of this species has been

reported to be 160 mm in body length in females (Tohoku Regional Fisheries

Research Lab., 1952). In the present study where maturity of individuals 0£

was estimated on the basis of'possession of mature eggs as well astwo

more conditions, the corresponding figure was 123 mm and about 507 of the

individuals were considered to mature at a body length of about 140 mm.

This discrepancy may be due to the smaller body size of this species found

off Niigata Prefecture than that in Pacific coastal waters (WADA, 1970).

V. Summary

Gonads of right-eyed flounder Limanda herzensteini caught off

Niigata Prefecture throughout a period between January 1968 and April

1969 were examined for their maturation process and spawning mode.

The results obtained are as follows:

1) The spawning season extended from March to May and its peak

appeared to occur in March and April.

2) Changes in the maturation process of the gonads as examined

histologically were essentially identical with those observed by

•

.2.

3,

17

YAMAMOTO (1953, 1954) for Liopsetta obscura.

3) The diameter composition of ova in the ovary, more than 0.1 (p.54)

mm, showed a monomodal distribution pattern so long as the ova remained

immature before the yolk globult stages ., the diameter kivi31ess than

0.5 mm. Among individuals carrying ova of the more developed stages

including the mature and the ripe egg stages, many were seen to show

a bimodal pattern of ovum diameter distribution, one mode at a diameter

corresponding to the yolk gloiyule stage, and the other at a diameter of

mature egg,

4) The standard body length at which about 50% of female specimens

reached maturity was estimated at 140 mm.

References

- — - .

(1957). ;5;eri'p.,117 J if I/ 4 . t*Ti)f • 711:71-:7:-.23tiregr-reu, (4): ------ • 2 (1959) . 4 7 -7 Sardinops inelanosticta (T. &S.) cOle..901.11'gqiest I ( -T110

(20) : 139-144. KAWASAKI, T. and M. HATANAKA (1951). Studies on the populations of the flatfishes in _Sendai. Bay.

•1. Liinanela angustirostris KITAHARA. Tohoku J. ilgri. Re., 2(1) : 83-104.,::-,._»:'•' -

i■,IATSCTRA, S. (1962). on the niaturation of the flatfish, Ganzô-Birame; Pselulo;htnnbus- 'cinnainbizens

(T. et S.). Rec. Ocean.W orks Japan. (6) : 31-40.

*iffi*:';--":-- 71 1- (1969a). •.•/ Y • if-311 1.Y.I.vc.-- v ,.--c. Met z3tÉ.15/ies,goplopmie;L-

!-="1--J- J I BP—PM -'1. : 34—e. • -- (1969b). v 21-3 CZ =2 11 V 4 a)

4F. le Tiff J I B P—Pm -tf : 38—

45. • É-f_I-.: 1C .11- 93 (1960) • :IL

FA..vigt. 7.K. -of 4r.

4. (6) : 157-171.

"ï7it (1952) . I g I I • - IL,ïf Ilei';!1:, (5) : 1 — 9 .

5. Miele (1970... "PriS., 1,11';l- PP.';' if --• et I .•jiz 71:..ii)fitità- , (22) : 31

—43. WHEELER, J. E. G. (1924). '1' he growth of the egg in the dal) (Pleuronectes liinand(1). Quart. I. Micro.

' Sci., 68 : 6-11-6(30. (1953).J.A ■ ci)jâii.i.u. -_. i ,..-19 - brOf31,.. 1 . P -f met, -,L,Kiimu,

• (8) : 52-62.

(195- 1 efil:fieDlene ;"S TilrAr, . .e p -f ,fiff,lapee-el,-:_i;..--c. :It* Qf

(.11) : 68-77. YANIÂSIOTO, K. (1956). Studies on the formation of fish eggs. I. Annual cycle in the development of

ovarian eggs in flounder, LioPsetta obscure. J. Fac. Sci. Hokkaido Univ..Ser. VI, Zoot., 12(3):

362-373, and II. YOSHIOKA (1964). Rhythm of development in the oocyte of the IVIedaka, OrYzias

latipes. Bull. Foe. Fish. Hokkaido Univ., 15 (1) : 5-19.

18

t. ISHII, R. (1957). Seijuku ni kansuru chosa. (3) Aka-garei (Studies on

maturation. 3. Hippoglossoides dubius). Hokusuiken--Hokusuishi

Shigenchosa Yoho (Condensed Report of A survey of Resources Carried

Out Jointly blthe Hokkaido Regional Fisheries Research Laboratory and

the Hokkaido Fisheries Experiment Station), 4: 61-78.

ISHII, R. et al. (1959). Maiwashi no sanran kaisu ni tsuite--Yoho (Spawn-

ing frequency in sardine Sardinops melanosticta T. & S.-- Preliminary

report). Hokusuiken Kenkyuhokoku (Bulletin of the Hokkaido Regional

Fisheries Research Laboratory), 20: 139-144.

MATSUURA, S. (1969a). Ishigarei no seijuku sanrangata ni tsuite. Naikai-

sei kaiiki ni okeru seibutsugunshu no seisan no dotai ni kansuru

kenkyu--43-nendo kenkyugyoseki hokoku (Maturation and spawning mode

of Kareius bicoloratus. Reproduction dynamics of organism populations

in inland sea areas--Research progress report for 1968). JIBP--PM

Section: 34-37.

MATSUURA, S. (1969b). Ishigarei oyobi makogarei no sanran ni kansuru

jikkenteki kansatsu. Naikaisei kaiiki ni okeru seibutsugunshu no

seisan no dotai ni kansuru kenkyu--43-endo kenkyugyoseki hoknku

(Experimental observations of spawning in Kareius bicoloratus and

Limanda yokohamae. Reproduction dynamics of organism populations

in inland sea areas--Research progress report for 1968). JIBP--PM

Section: j8-45.

3. OUCHI, A. and OGATA, T. (1960). Hokubu Nihonkai sokobiki kin5yoku no

dobutsu bunpu ni kansuru kenkyu. I. Teisei yogyo (Studies on the

distribution of animals in trawling-prohibited areas of the northern

Japan Sea. I. Benthic fry). Nissuiken Nenpo (Annual Report of the

Japan Sea Regional Fisheries Research Laboratory), 6: 157 - 171.

4. Tohoku Regional Fisheries Research Laboratory (1952). Kisen sokobiki-ami

gyogyo no kinshi kaiiki to amime ni tsuite (Trawling-prohibited areas

and net mesh size). Tohoku Suiken Sosho (Serial Publications from

the Tohoku Regional Fisheries Research Laboratory), 5: 1-9.

2.

19

5. WADA, K. (1970). Niigata-ken okiaisan magarei no shigen seibutsugakuteki

kenkyu. I. Nenrei to seicho (Studies on the population biology of

right-eyed flounder Limanda herzensteini off Niigata Prefecture).

Nissuiken Hokoku (Bulletin of the Japan Sea Regional Fisheries Res.

Lab.), 22: 31-43.

C. YAMAMOTO, K. (1953). Kaisan gyorui no seijukudo ni kansuru kenkyu. I.

Kurogarei no seiso no kisetsuteki junkan (Studies on maturity of

marine fishes. I. Seasonal cycle of spermary in Liopsetta obscura).

Hokusuiken Hokoku (Bulletin of the Hokkaido Regional Fisheries Res.

Lab.), 8: 52-62.

YAMAMOTO, K. (1954). Kaisan gyorui no seijukudo ni kansuru kenkyu.

Kurogarei no mesugyo no seijukudo ni tsuite (Studies on maturity of

marine fishes. IL Maturity of female flounder Liopsetta obscura).

Ditto. 11: 68-77.

{.

20

Explanation of Plates

Plate I Ova of variouFyinaturation stages in ovaries

1. Peripheral nucleus stage x514

2. Yolk vesicle stage to primary yolk globule stage x180

3. Primary yolk globule stage x210

4. Secondary yolk globule stage x130

5. Tertiary yolk globule stage x126

6. Germinal cell-moving stage x130

7. Prematured egg stage x123

8. Matured egg stage x86

Plate II Yolk and spermaries of various maturation stages

9. ovary containing ova of the secondary--tertiary yolk globulestage, from an individual showing a bimodal pattern of ovum

diameter distribution x32

10. empty follicles x11311. aborted egg being absorbed x630

12. remaining egg being absorbed x124

13. Spermatogonia x800

14. Spermatocytes x740

15. Spermatocytes x77016. Spermatozoa x740

Sections 4 to 6, 9, 13, 15, and 16 were stained with Heidenhain's iron

hematoxylin--light green, whereas the others with Meyer's hemalum--eosin.

:11à

•

El I Plate I

4

î

CI . )1k e E91 •

1111L5 erref,'.;:e1M0910 1,q11

1. NM x 514

2. 1 .x 180

3. mil ivivel X 210

4. e; 2 ?5[l 130

5. . e; 3 '15( enu:Ritii X 126

6. JJJI 43 x 130

7. irJiWJ x 123

S. ÏiilYj x85

w II pile errA (DM

9. Wi 2 • 3 i;;:. 1 0 eiWR »- »YM.It11 4'., 9-11// , ;â91 1 Miii`;iii 2 10. IM:Olie (empty follicle) x 113

11. I.V5.1U ber.: 911 X630

12. fee x 124

13. 1IjIJ X 800 14. iiiiI;kff.1114:d X740

15. . x770

16. ;h:T X 740 .

4 — , 9, 13, 15, 16L ..1 ,-, -( 52 :/-•-f ‘45:-- -;' / 9 f F 9 — -f -', •

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